New files.

Rev: src/nettle/base16-decode.c:1.1
Rev: src/nettle/base16-encode.c:1.1
Rev: src/nettle/base16-meta.c:1.1
Rev: src/nettle/base16.h:1.1

1 files changed, 127 insertions, 0 deletions

diff --git a/base16-decode.c b/base16-decode.c
new file mode 100644
index 00000000..a5e6185c
--- /dev/null
+++ b/base16-decode.c
@@ -0,0 +1,127 @@
+/* base16-encode.c
+ *
+ * Hex decoding.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2002 Niels Möller
+ *  
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ * 
+ * The nettle library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+ * License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+ 
+#include "base16.h"
+
+#include <assert.h>
+#include <stdlib.h>
+
+void
+base16_decode_init(struct base16_decode_ctx *ctx)
+{
+  ctx->word = ctx->bits = 0;
+}
+
+enum { HEX_INVALID = -1, HEX_SPACE=-2 };
+
+static const signed char
+hex_decode_table[0x80] =
+  {
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1, 
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+     0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1,
+    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+  };
+
+/* Decodes a single byte. Returns amount of output (0 or 1), or -1 on
+ * errors. */
+int
+base16_decode_single(struct base16_decode_ctx *ctx,
+		     uint8_t *dst,
+		     uint8_t src)
+{
+  int digit;
+
+  if (src >= 0x80)
+    return -1;
+
+  /* FIXME: This code could use more clever choices of constants. */
+  digit = hex_decode_table[src];
+  switch (digit)
+    {
+    case -1:
+      return -1;
+    case -2:
+      return 0;
+    default:
+      assert(digit >= 0);
+      assert(digit < 0x10);
+
+      if (ctx->bits)
+	{
+	  *dst = (ctx->word << 4) | digit;
+	  ctx->bits = 0;
+	  return 1;
+	}
+      else
+	{
+	  ctx->word = digit;
+	  ctx->bits = 4;
+	  return 0;
+	}
+    }
+}
+
+int
+base16_decode_update(struct base16_decode_ctx *ctx,
+		     unsigned *dst_length,
+		     uint8_t *dst,
+		     unsigned src_length,
+		     const uint8_t *src)
+{
+  unsigned done;
+  unsigned i;
+
+  assert(*dst_length >= BASE16_DECODE_LENGTH(src_length));
+  
+  for (i = 0, done = 0; i<src_length; i++)
+    switch(base16_decode_single(ctx, dst + done, src[i]))
+      {
+      case -1:
+	return 0;
+      case 1:
+	done++;
+	/* Fall through */
+      case 0:
+	break;
+      default:
+	abort();
+      }
+  
+  assert(done <= BASE16_DECODE_LENGTH(src_length));
+
+  *dst_length = done;
+  return 1;
+}
+
+int
+base16_decode_final(struct base16_decode_ctx *ctx)
+{
+  return ctx->bits == 0;
+}